Hammer actuating mechanism and drum design for printers

ABSTRACT

A magnetic field structure for printers has a pair of opposed Ushaped pole pieces arranged to form a parallel pair of extended gaps in which high flux density exists. In one embodiment of a dot matrix printer, a single, narrow, vertical blade disposed to strike against raised portions of a drum is pivotally mounted on a carriage which rides along one pole piece. A flat, rectangular coil is disposed in the magnet gaps with one end of the coil connected to the hammer blade.

United States. Patent 1191 Hell 197/1 R X Amada, 101/93 C X Kleinschmidt et a1. 101/93 C X Reese et a1 101/93 C X Hoyer 1 Apr. 16, 1974 HAMMER ACTUATING MECHANISM AND 3,453,648 7/1969 Stegenga 101/93 c x DRUM DESIGN FOR PRINTERS 3,606,834 9/1971 Nyman et a1... 101/93 C i 3,618,514 11/1971 Nyman et a1... 101/93 C [75] Inventor: Sigurd Hoyer, Hunt1ngton, 3,625,142 12/1971 Bresler 101/93 c Assignee: Potter Instrument p y, 3,651,916 3/1972 Brecchi 101/93 C Plainview, NY. v V

Primary ExammerRobert E. Pulfrey Filed! 2 1971 Assistant Examiner-Eugene H. Eickholt [21] APPL NW 174,476 Attorney, Agent, or Firm-Lane, Aitken, Dunner &

. Ziems [52 US. Cl. 101/93 C, 197/1 R, 1.97/49 I [51] 1m. (:1 B4lj 5/00 [5 ABSTRACT Of Search C; R, A magnetic structure for printers has a pair of opposed U-shaped pole pieces arranged to form a par- 1 References Clted allel pair of extended gaps in which high flux density v UNITED STATES PATENTS exists. In one embodiment of a dot matrix printer, a 2,658,106- 1 1/ 195 3" Single, narrow, vertical blade disposed to strike against raised portions of a drum is pivotally mounted on a carriage which rides along one pole piece. A flat, rectangular coil is disposed in the magnet gaps with one end of the coil connected to the hammer blade.

9 Claims, 10 Drawing Figures PATENTEDAPR I6 190. I 3.804.008

SHEET 1 UF 3 IN VENTOR 25 5 SIGURD HOYER ATTORNEYS FATENTEDAPR 15 I974 3,804,008

SHEET 3 [IF 3 F /G /0. 9 'I E CHARACTER W|D T H I "I PCHARACTER WIDTH AK 7;

6 N 7 ll 8 3 DRUM CIRCUMFERENCE 4 v 5 DRUM CIRCUMFERENCE 7 A, ll

-'HAMME R WIDTH F/G .7 V s 0 PiAMMER WIDTH F/G INVENTOR SIGURDHOYER BY t W HAMMER ACTUATING MECHANISM AND DRUM DESIGN FOR PRINTERS BACKGROUND OF THE INVENTION The invention relates generally to the field of high speed printing apparatus for composing printed information in response to electrical signals by means of discrete print units such as dots and bars, and more specifically, the invention pertains to improved hammeract'uating assemblies for such printers and to improved means for printing with unconventional patterns.

One problem in so-called high speed printers is providing a suitable actuating mechanism for the hammers. Accordingly, the general purpose of this invention is to provide an improved hammer actuator employing an extended stationary magnetic field. Another object ofthe invention is to provide a novel printer using a line segment pattern on a drum for forming the characters.

Briefly, this invention contemplates the provision of an extended magnetic field structure parallel and adjacent to a revolving drum. A hammer blade, pivotally mounted on a movablecarriage, is disposed to strike against raised portions of the circumference of the drum to print dots or other symbols on paper inserted between the drum and the hammer blade. The extended magnetic field structure comprises a pair of opposed pole pieces of U-shaped cross-section forminga pair of parallel gaps. A flat coil in the magnet gaps is connected to the hammer blade for actuating it.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of one embodiment of a printer constructed according to the invention.

FIG. 2 is a cross-sectional view taken along lines 2-2 of FIG. 1 illustrating the magnetic field structure and flat coil.

FIG. 3 is a cross-sectional view taken along lines 3-3 of FIG. 2 providing a plan view of the coil.

FIG. 4 is a plan view of a typical helix printer constructed according to the invention.

FIG. 5 is a cross-sectional view taken along lines 55 of FIG. 4.

FIG. 6 is a cross-sectional view taken along lines 6-6 of FIG. 5 providing a plan view of the coils.

FIG. 7 is a schematic representation illustrating the elements in pattern for printing alpha-numeric characters by using selected combinations of raised elements.

FIG. 8 illustrates representative characters in a font composed of the elements in the pattern of FIG. 7.

FIG. 9 is a development of asection of the surface of a drum for use in a printer in accordance with one aspect of the invention.

FIG. 10 is a view similar to that of FIG. 9 showing another embodiment of. the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIGS. 1, 2 and 3 of the drawings, an extended magnetic field structure 10 is arranged parallel and adjacent to a rotating drum '11 having longitudinal ribs 12. Field structure 10 comprises upper and lower pole pieces 14 and 15 having U-shaped cross-sections. The pole pieces are supported in a suitable manner (not shown) to form gaps 8 and 9. A magnetizing coil 16 produces a strong magnetic field through these gaps.

A carriage 18 is disposed on the flat upper surface of magnet 14 for linear travel along the length thereof parallel to the axis of drum 11. A set of three horizontal wheels 19 insures constant lateral positioning of the carriage with respect to the drum. One or more of the wheels 19 may be urged inwardly by suitable resilient means to. facilitate mounting and to regulate the frictional contact of the horizontal wheels with the side walls of magnet 14. A set of three vertical wheels 20 provides low friction support for linear movement of carriage 18 on magnet 14. It should be understood that wheels 19 and 20 represent only one form of guide means for carriage 18; other suitable equivalent means are usable in the practice of the invention.

A hammer 22 having a curved blade face 22a, mounts perpendicularly with respect to the travel of carriage 18, is pivotally connected by a flexure hinge 23 to carriage 18. Hinge 23 includes a downwardly extending rigid flat portion 23a to which the lower end of hammer 22 is secured. When hammer 22 is pivoted (counterclockwise in FIG. 2) a blade face 22a is forced against one of ribs 12 on drum 11.Ink ribbon 25 and paper (not shown) are carried between blade face 22a and drum 11. When face 22a is forced against ribs 12, a dot is printed at the blade/rib intersection-It should be noted that the spacing of ribs 12 about the drum axis corresponds to the length of face 22a. By timing the actuation of hammer 22, a column of dots, or selected dots within the column, may be printed at one position of carriage 18. By advancing carriage 18 in steps by means of cables 27 operated by suitable, controlled drive means (not shown), a plurality of dot columns may be printed to form a matrix. By selecting the appropriate combination of dots in the matrix, and actuating the hammer only at those times, alpha-numeric characters can be composed. The carriage may be given continuous movement if the blade face 22 is tilted slightly from the vertical so that the upper end leads the lower end.

The lower portion 23a of flexure hinge 23 is connected to a flat coil 25 formed of a plurality of turns of wire cemented together and suspends the coil 25 in the gaps 8 and 9. When coil 25 is energized through conductive leads 26a and 26b, the coil will move to the right (assuming a current of the proper direction) in the direction of its own plane, carrying connected hinge portion 23a along with it and thus pivoting hammer blade 22 against the drum. Since the gaps between magnets 14 and 15 are uniform along the length of the carriage travel path, hammer blade 22 can be actuated with the same force in any position along the length of the drum.

Referring now to FIGS. 4, 5 and 6, another embodiment of the invention is shown for use with a printer having a drum 11 with a helical-rib 31 formed around the outer circumference thereof. A pair of opposed channel magnets 14 and 15 are arranged in the same relationship to each other and to the drum as in FIG. 1 for the matrix printer. However, a plurality of horizontally-aligned hammer blades, unmovable along the axis of the drum 11', are used instead of a carriagemounted vertical hammer blade. Each hammer blade 32 is mounted parallel and adjacent to drum 11' and has a length corresponding to the adjacent convolution of helical rib 31. Each hammer blade 32 can be separately fired against its corresponding helical rib. As drum 11' rotates, the intersection of each hammer blade and its corresponding portion of rib 31 moves continuously to the right so that by firing the blade at predetermined times, a selective succession of dots may be printed along the line of hammers. Each hammer blade is secured to a flat coil 25 like that used for the carriage-mounted hammer blade of FIGS. 1, 2 and 3. Flat coil 25 is similarly oriented between the gaps of magnets 14 and 15. Blade 32 lies in the same plane as that of coil 25 and is secured to the end of coil 25 adjacent to the drum. Coil 25 is supported by leaf springs 34 perpendicular with respect to the plane of the coil attached to magnet or 14, if desired. Leaf springs 34 are arranged to resist movement of blade 32 against drum 11' so that when current of the proper polarity is introduced via a suitable conductor (not shown) carried in the leaf springs, and hammer 32 is forced against the drum, its quick return is assisted by action of the springs.

Paper and ink ribbon (not shown) are carried between blades 32 and drum ll of the helix printer. By advancing the paper in steps, a succession of horizontal lines of selected dots can be printed on the page, each line simultaneously, to compose alpha-numeric characters. Because of the ability of the printer to print one horizontal line of dots at a time, it is particularly useful in facsimile printing where the original document is scanned along a narrow scan line, one scan line at a time, to provide a series of electrical signals to drive coils 25 of the helix printer.

A line segment pattern producing a highly readable character font is shown in FIG. 7. The elements of a starburst, as shown in FIG. 7, are separated for clarity but are arranged in practice to be contiguous so as to form continuous lines which can be selectively combined for character composition. A sample of the pattern is shown in FIG. 8. The elements of the starburst (FIG. 7) which bear the same numeral, differ among themselves only in vertical positioning. For example, elements 1 are all parallel and lie in the same horizontal position but are spaced from each other vertically. It should be noted, however, that the diagonal elements 6, 7, 8 and 9 are all discrete in that they differ from each other by more than one parameter. For example, diagonal element 8 differs from element 9 in both orientation and vertical positioning. While there are actually 19 different parts which make up the starburst pattern, because of the exclusively vertically displacement ofthe horizontal and vertical bars and connective dots, the number of discrete elements which need to be separately represented is 10 instead of 19.

The basic approach to implementing a starburst printer is to replace the longitudinal or helical ribs on the drum surface with a plurality of short bar-like projections to form the horizontal, vertical and diagonal elements of the starburst and small cylindrical projections to form the dots, in a pattern such that the hammer blades may be repeatedly actuated to compose the characters by timed positioning of selected elements in a given character space.

Referring now to FIG. 9, a typical implementation of the starburst printer is illustrated. The figure represents the surface of drum 11 (FIG. 1), cut and laid flat to facilitate a view of all 360 of the surface. The vertical divisions represent circumferential ring-like sections on the drum surface corresponding to the width of one character space. The stippled areas 22a in FIG. 9 represent the area covered by the modified face of hammer blade 22. Blade face 22a has a width corresponding to two characters or two ring-like sections, unlike the linear blade face 22a of FIG. 2 for printing dots in the conventional matrix format. Areas 22a, it should be noted, represent a single hammer blade and are repeated to show the relative motion between rotating drum 11 and hammer 22, as hammer 22 moves along the drum axis to the right. The height of blade face 22a corresponds to the height of one character, thus the area covered within one section by hammer blade 22a is termed a character block since it corresponds to an entire character space having a height equal to the blade face and a width equal to the section width. Thus the horizontal divisions on the drum surface (FIG. 9) form boxes representing the character blocks. The discrete elements 1-10 of the starburst pattern are located in 10 consecutive character blocks in the first section (column), and are distributed over about the circumference of the section. In the next section (second column), the identical 10 discrete elements are arranged in consecutive blocks to cover the alternate 180 segment about the drum. In the third circumferential section, the 10 discrete elements are again located in the first 180 segment of consecutive character blocks.

It should be noted that the speed of the hammer travel must be synchronized in a particular way with the rotation of the drum in FIG. 8. The speed of hammer blade 22 must be such that the time required for the trailing edge 41 of blade face 22a to sweep over one section, such as section 4, corresponds to a half revolution of the drum during which time 10 character blocks pass in front of blade face 22a.

Referring again to FIG. 7, elements 1, 2, 3, 4, 5 and 10 may be positioned in the upper, middle or lower location respectively by properly timing the striking blows of hammer 22. Although the hammer blade is continuously traveling to the right, the paper on which a given character is being composed is stationary while one line is being printed. Thus, while drum 11 completes a half revolution and the hammer face 22a moves over one section, a single alpha-numeric character is formed by selective timing of the hammer blows. For example, to compose the letter T, element 1 would be struck at the upper position, element 2 would be struck at the upper position, element 4 would be hit in both its upper and lower positions, and dot 10 would be struck at all three of its positions.

Referring now to FIG. 10, a similar view of the surface of drum 11' is shown covered with an appropriate arrangement of bars and dots for printing the starburst pattern characters by means of a plurality for horizontal, longitudinally-stationary blades. The stippled areas in FIG. 10 correspond to the areas covered by blade faces 32a. The blade faces represented by area 32a cover an area so that bars as well as dots can be printed. The drum surface is again divided into a number of ring-like sections of circumferential character blocks, each corresponding to the character space. The vertical width of face area 320 again corresponds to the height of one character. Elements l-l0 of the starburst pattern of FIG. 7 are distributed around the entire circumference of each section to cover 360. On one section the spacing between two elements, such as element 1 and element 2 in the first section, corresponds to the hammer blade width, that is, the number of characters which each hammer blade spans. The elements distributed in adjacent sections under one hammer are all spaced equally, but are staggered or offset by one block in each successive section. For example, element 1 is in character block 1 in the first section, but element 1 is in character block 2 in the second section, and so forth. The elements are staggered in this manner so that the blade face can only strike one element at a time. The vertical positioning of the elements is accomplished by appropriate timing of the hammer blows. During one revolution of the drum in FIG. 10, three characters (or any number of characters spanned by one blade) can be simultaneously composed. For example, to form three Ts in a row, element 1 is struck in the upper position for all three characters first, then element 2 might be struck in the upper position for all three characters. Next, all three characters receive element 4 in the upper and then the lower position. And finally, all three characters receive dots in all three positions.

It should be noted that the order of the elements on the drum within a ring-like section is not important, so long as all of the discrete elements appear somewhat in the character blocks on each section.-

Having been presented with this particular implementation of the starburst pattern, those skilled in the art of printer design will immediately recognize that other linesegment patterns for composing characters can be similarly distributed over the surface of the rotating drum.

It will be understood that various changes in the details, materials, steps and arrangements of parts which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle'and scope of the invention as expressed in the appended claims.

What is claimed is:

1. A printer, comprising a rotatable drum, a pair of stationary magnetic pole pieces arranged beside said drum to form a pair of parallel magnetic field gaps extending along the length of said drum parallel to its rotational axis, a carriage mounted alongside said drum for travel parallel to said drum axis, means for moving said carriage, a flat electrical coil operatively disposed in said gaps, a printing hammer, an elongated member interconnecting said hammer and said coil, said member being pivotally connected to said carriage to permit pivoting of said coil and hammer together in a plane approximately perpendicular to said drum axis so that said hammer strikes against said drum to print when said coil is operatively energized, means for energizing said coil, the magnetic field in said gaps being so oriented that when it is energized said coil moves in said gaps in a direction to pivot said hammer against said drum.

2. The printer of claim ll, wherein said pole pieces include opposed elongated members of U-shaped cross section with the north pole of each member-in spaced opposition to south pole of the other member, said carriage being mounted on top of one of said U-shaped members, said interconnecting member extending between said drum and the side of said one U-shaped member to connect said coil in said gaps to said carriage and hammer.

3. The printer of claim 1 wherein said drum has longitudinal ribs formed on its surface spaced about said drum axis and'parallel thereto, said hammer extending perpendicularly relative to said drum axis.

4. The printer of claim 3 wherein said carriage includes a set of wheels parallel to the drum axis and a set of wheels perpendicular to the drum axis for rolling longitudinal and lateral support respectively.

5. The printer of claim 1, wherein the surface of said drum is divided perpendicularly to the drum axis into a plurality of successive contiguous ring-like sections each containing a number of equal-sized character blocks spaced around its circumference, said hammer having a blade with a length parallel to the drum axis equal to the width of two adjacent sections and a width perpendicular to the drum axis equal to the height of one character block, said drum having formed on the surface thereof a plurality of raised portions each corresponding to one element of a composite character set of different spatially related elements representing a predetermined geometric pattern, selected combinations of said spatially related elements of pattern forming individual alphanumeric characters, each section having said raised portions located in respective, consecutive blocks corresponding to all of the elements in said set, adjacent sections having said character blocks containing raised portions positioned in opposite segments.

6. A character printer comprising a rotatable drum, a plurality of hammer blades parallel to each other and to the drum axis and aligned along the length of the drum, a plurality of hammer actuating means connected respectively to said hammers for selectively urging said hammers against said drum, the surface of said drum being divided perpendicularly to its axis into a plurality of successive contiguous ring-like sections each containing a number of equal-sized consecutive character blocks spaced around the circumference of each ring-like section, each said hammer blade having a blade face with a length parallel to said drum axis spanning n sections, where n is an integer, and a width perpendicular to the drum axis corresponding to the height of one character block, the surface of said drum having raised portions formed thereon corresponding to elements in a composite character set of different spatially related elements representing a predetermined geometric pattern, selected combinations of said spatially related elements of said pattern forming individual alphanumeric characters, raised portions representing all of the elements in said set being spaced around each section, one in every nth character block, corresponding ones of said projections being offset by one character block in each successive section spanned by each hammer blade, said raised portions being vertically positionable in a character space by means of pre-' determined timing of the actuation of said hammer blade by said actuation means.

7. The printer of claim 6 wherein said set of elements comprises a predetermined number of discrete continuous line-segment elements which correspond to a pattern having a number of separate line segment parts greater than said predetermined number of elements in said set.

8. A printer having a rotatable drum and a hammer blade arranged adjacent to said drum for linear movement in the direction of the drum axis, actuation means connected to said hammer blade and movable therewith for causing said hammer blade to strike against the surface of said drum, said drum surface being divided perpendicularly to the drum axis into a plurality of contiguous ring-like sections each composed of a plurality of consecutive equal-sized character blocks located about the circumference thereof, said hammer blade having a blade face with a length parallel to the drum axis spanning two adjacent sections and a width perpendicular to the drum axis corresponding to the height of one character block, a plurality of raised portions corresponding to each element in a composite character set of different spatially related elements representing a predetermined geometric pattern, selected combinations of said spatially related elements of said pattern forming individual alphanumeric characters,

raised portions representing all of said elements being located in a segment of consecutive character blocks in each ring-like section, the raised portions located in two adjacent sections being disposed in opposite 180 segments, said raised portions being positionable vertically in a character space by predetermined timing of the hammer blade actuation by said actuation means.

9. The printer of claim 8 wherein said set of elements comprises a predetermined number of discrete continuous line segment elements which correspond to a pattern having a number of line segment parts greater than said predetermined number of elements. 

1. A printer, comprising a rotatable drum, a pair of stationary magnetic pole pieces arranged beside said drum to form a pair of parallel magnetic field gaps extending along the length of said drum parallel to its rotational axis, a carriage mounted alongside said drum for travel parallel to said drum axis, means for moving said carriage, a flat electrical coil operatively disposed in said gaps, a printing hammer, an elongated member interconnecting said hammer and said coil, said member being pivotally connected to said carriage to permit pivoting of said coil and hammer together in a plane approximately perpendicular to said drum axis so that said hammer strikes against said drum to print when said coil is operatively energized, means for energizing said coil, the magnetic field in said gaps being so oriented that when it is energized said coil moves in said gaps in a direction to pivot said hammer against said drum.
 2. The printer of claim 1, wherein said pole pieces include opposed elongated members of U-shaped cross section with the north pole of each member in spaced opposition to south pole of the other member, said carriage being mounted on top of one of said U-shaped members, said interconnecting member extending between said drum and the side of said one U-shaped member to connect said coil in said gaps to said carriage and hammer.
 3. The printer of claim 1 wherein said drum has longitudinal ribs formed on its surface spaced about said drum axis and parallel thereto, said hammer extending perpendicularly relative to said drum axis.
 4. The printer of claim 3 wherein said carriage includes a set of wheels parallel to the drum axis and a set of wheels perpendicular to the drum axis for rolling longitudinal and lateral support respectively.
 5. The printer of claim 1, wherein the surface of said drum is divided perpendicularly to the drum axis into a plurality of successive contiguous ring-like sections each containing a number of equal-sized character blocks spaced around its circumference, said hammer having a blade with a length parallel to the drum axis equal to the width of two adjacent sections and a width perpendicular to the drum axis equal to the height of one character block, said drum having formed on the surface thereof a plurality of raised portions each corresponding to one element of a composite character set of different spatially related elements representing a predetermined geometric pattern, selected combinations of said spatially related elements of pattern forming individual alphanumeric characters, each section having said raised portions located in respective, consecutive blocks corresponding to all of the elements in said set, adjacent sections having said character blocks containing raised portions positioned in opposite 180* segments.
 6. A character printer comprising a rotatable drum, a plurality of haMmer blades parallel to each other and to the drum axis and aligned along the length of the drum, a plurality of hammer actuating means connected respectively to said hammers for selectively urging said hammers against said drum, the surface of said drum being divided perpendicularly to its axis into a plurality of successive contiguous ring-like sections each containing a number of equal-sized consecutive character blocks spaced around the circumference of each ring-like section, each said hammer blade having a blade face with a length parallel to said drum axis spanning n sections, where n is an integer, and a width perpendicular to the drum axis corresponding to the height of one character block, the surface of said drum having raised portions formed thereon corresponding to elements in a composite character set of different spatially related elements representing a predetermined geometric pattern, selected combinations of said spatially related elements of said pattern forming individual alphanumeric characters, raised portions representing all of the elements in said set being spaced around each section, one in every nth character block, corresponding ones of said projections being offset by one character block in each successive section spanned by each hammer blade, said raised portions being vertically positionable in a character space by means of predetermined timing of the actuation of said hammer blade by said actuation means.
 7. The printer of claim 6 wherein said set of elements comprises a predetermined number of discrete continuous line-segment elements which correspond to a pattern having a number of separate line segment parts greater than said predetermined number of elements in said set.
 8. A printer having a rotatable drum and a hammer blade arranged adjacent to said drum for linear movement in the direction of the drum axis, actuation means connected to said hammer blade and movable therewith for causing said hammer blade to strike against the surface of said drum, said drum surface being divided perpendicularly to the drum axis into a plurality of contiguous ring-like sections each composed of a plurality of consecutive equal-sized character blocks located about the circumference thereof, said hammer blade having a blade face with a length parallel to the drum axis spanning two adjacent sections and a width perpendicular to the drum axis corresponding to the height of one character block, a plurality of raised portions corresponding to each element in a composite character set of different spatially related elements representing a predetermined geometric pattern, selected combinations of said spatially related elements of said pattern forming individual alphanumeric characters, raised portions representing all of said elements being located in a 180* segment of consecutive character blocks in each ring-like section, the raised portions located in two adjacent sections being disposed in opposite 180* segments, said raised portions being positionable vertically in a character space by predetermined timing of the hammer blade actuation by said actuation means.
 9. The printer of claim 8 wherein said set of elements comprises a predetermined number of discrete continuous line segment elements which correspond to a pattern having a number of line segment parts greater than said predetermined number of elements. 